Glass-reinforced fluoropolymer compositions

Abstract

A glass-reinforced fluoropolymer composition has increased flexural strength and includes a first fluoropolymer, a second fluoropolymer, and glass fibers. The first fluoropolymer is present in an amount of from 60 to 99 parts by weight per 100 parts by weight of the glass-reinforced fluoropolymer composition. The second fluoropolymer is chosen from (1) a carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer, (2) a carboxy- and/or anhydride-functionalized poly(ethylene-co-tetrafluoroethylene) copolymer, and (3) combinations thereof. The second fluoropolymer is present in an amount of from 0.5 to 39.5 parts by weight per 100 parts by weight of the glass-reinforced fluoropolymer composition. The glass fibers are present in an amount of from 0.5 to 39.5 parts by weight per 100 parts by weight of the glass-reinforced fluoropolymer composition.

What is claimed is: 
     
       1. A glass-reinforced fluoropolymer composition having increased flexural strength and comprising:
 A. a first fluoropolymer present in an amount of from 60 to 99 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition; 
 B. a second fluoropolymer defined as a carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer, wherein said second fluoropolymer is present in an amount of from 0.5 to 39.5 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition; and 
 C. glass fibers having a diameter of from 5 to 20 microns and a length of 5 to 100 microns, with said glass fibers present in an amount of from 0.5 to 39.5 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition; 
 
       wherein said glass fibers are milled fibers, and 
       wherein said carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer consists of units derived from:
 (1) tetrafluoroethylene, 
 (2) a cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group, and 
 (3) a monomer selected from the group of:
 (a) CF 2 ═CFOR f1 , wherein R f1  is a C 1-10  perfluoroalkyl group which may contain an oxygen atom between carbon atoms, 
 (b) CF 2 ═CFOR f2 SO 2 X 1 , wherein R f2  is a C 1-10  perfluoroalkylene group which may contain an oxygen atom between carbon atoms, and X 1  is a halogen atom or a hydroxyl group, 
 (c) CF 2 ═CFOR f2 CO 2 X 2 , wherein R f2  is as defined above, and X 2  is a hydrogen atom or a C 1-3  alkyl group, 
 (d) CF 2 ═CF(CF 2 ) p OCF═CF 2 , wherein p is 1 or 2, and 
 (e) combinations thereof. 
 
 
     
     
       2. The glass-reinforced fluoropolymer composition of  claim 1  wherein said cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group is selected from itaconic anhydride, citraconic anhydride, and combinations thereof. 
     
     
       3. The glass-reinforced fluoropolymer composition of  claim 1  wherein said second fluoropolymer is present in an amount of from 5 to 20 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition. 
     
     
       4. The glass-reinforced fluoropolymer composition of  claim 3  wherein said glass fibers are present in an amount of from 15 to 35 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition. 
     
     
       5. The glass-reinforced fluoropolymer composition of  claim 1  wherein said glass fibers have a bulk density of from 0.5 to 1.5 g/ml. 
     
     
       6. The glass-reinforced fluoropolymer composition of  claim 4  wherein said glass fibers have a diameter of from 8 to 15 microns, a length of from 15 to 85 microns, and a bulk density of from 0.6 to 1 g/ml. 
     
     
       7. The glass-reinforced fluoropolymer composition of  claim 1  wherein said first fluoropolymer is present in an amount of from 80 to 95 parts by weight per 100 parts by weight of said glass-reinforced fluoropolymer composition. 
     
     
       8. The glass-reinforced fluoropolymer composition of  claim 1  wherein said first fluoropolymer is chosen from a perfluoroalkoxy polymer, poly(ethylene-co-tetrafluoroethylene), polyvinylidene fluoride, fluorinated ethylene propylene, and combinations thereof. 
     
     
       9. The glass-reinforced fluoropolymer composition of  claim 1  wherein said glass fibers are untreated and optionally free of silane. 
     
     
       10. The glass-reinforced fluoropolymer composition of  claim 1  having a flexural strength that is from 15 to 40 percent greater than a comparative composition that is free of said second fluoropolymer, as determined using ASTM D790-10. 
     
     
       11. The glass-reinforced fluoropolymer composition of  claim 10  having a flexural modulus that is from 25 to 60 percent greater than a comparative composition that is free of said second fluoropolymer, as determined using ASTM D790-10. 
     
     
       12. The glass-reinforced fluoropolymer composition of  claim 1  having a compressive strength that is from 10 to 25 percent greater than a comparative composition that is free of said second fluoropolymer, as determined using ASTM D95-10. 
     
     
       13. The glass-reinforced fluoropolymer composition of  claim 12  having a compressive modulus that is from 40 to 70 percent greater than a comparative composition that is free of said second fluoropolymer, as determined using ASTM D95-10. 
     
     
       14. The glass-reinforced fluoropolymer composition of  claim 1  having a tensile modulus that is from 80 to 125 percent greater than a comparative composition that is free of said second fluoropolymer, as determined using ASTM D638-10. 
     
     
       15. A method of forming a glass-reinforced fluoropolymer composition comprising the steps of:
 forming a melt stream of a first fluoropolymer; 
 mixing glass fibers and a second fluoropolymer defined as a carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer to form a mixture; and 
 adding the mixture to the melt stream to form the glass-reinforced fluoropolymer composition; 
 wherein the glass-reinforced fluoropolymer composition includes the first fluoropolymer in an amount of from 60 to 99 parts by weight, the second fluoropolymer in an amount of from 0.5 to 39.5 parts by weight, and the glass fiber in an amount of from 0.5 to 39.5 parts by weight, each based on 100 parts by weight of the glass-reinforced fluoropolymer composition; 
 wherein the glass fibers have a diameter of from 5 to 20 microns and a length of 5 to 100 microns; and 
 wherein said glass fibers are milled fibers, and 
 wherein the carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer consists of units derived from:
 (1) tetrafluoroethylene, 
 (2) a cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group, and 
 (3) a monomer selected from the group of:
 (a) CF 2 ═CFOR f1 , wherein R f1  is a C 1-10  perfluoroalkyl group which may contain an oxygen atom between carbon atoms, 
 (b) CF 2 ═CFOR f2 SO 2 X 1 , wherein R f2  is a C 1-10  perfluoroalkylene group which may contain an oxygen atom between carbon atoms, and X 1  is a halogen atom or a hydroxyl group, 
 (c) CF 2 ═CFOR f2 CO 2 X 2 , wherein R f2  is as defined above, and X 2  is a hydrogen atom or a C 1-3  alkyl group, 
 (d) CF 2 ═CF(CF 2 ) p OCF═CF 2 , wherein p is 1 or 2, and 
 (e) combinations thereof. 
 
 
 
     
     
       16. The glass-reinforced fluoropolymer composition of  claim 1  wherein said carboxy- and/or anhydride-functionalized perfluoroalkoxy copolymer consists of units derived from:
 (1) tetrafluoroethylene, 
 (2) a cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group, and 
 (3) perfluoropropyl vinyl ether.